It is often desirable and frequently necessary to sample or test a portion of tissue from humans and other animals, particularly in the diagnosis and treatment of patients with cancerous tumors, pre-malignant conditions, and other diseases or disorders.
Typically, in the case of breast cancer, there is a great emphasis on early detection and diagnosis through the use of screening modalities, such as physical examination, and particularly mammography, which is capable of detecting very small abnormalities, often nonpalpable. When the physician establishes by means of a mammogram or other screening modality that suspicious circumstances exist, a biopsy must be performed to capture tissue for a definitive diagnosis as to whether the suspicious lesion is cancerous. Biopsy may be done by an open or percutaneous technique. Open biopsy, which is an invasive surgical procedure using a scalpel and involving direct vision of the target area, removes the entire mass (excisional biopsy) or a part of the mass (incisional biopsy). Percutaneous biopsy, on the other hand, is usually done with a needle-like instrument through a relatively small incision, blindly or with the aid of an artificial imaging device, and may be either a fine needle aspiration (FNA) or a core biopsy. In FNA biopsy, individual cells or clusters of cells are obtained for cytologic examination and may be prepared such as in a Papanicolaou smear. In core biopsy, as the term suggests, a core or fragment of tissue is obtained for histologic examination which may be done via a frozen section or paraffin section.
The type of biopsy utilized depends in large part on circumstances present with respect to the patient, including the location of the lesion(s) within the body, and no single procedure is ideal for all cases. However, core biopsy is extremely useful in a number of conditions and is being used more frequently by the medical profession.
A very successful type of image guided percutaneous core breast biopsy instrument currently available is a vacuum-assisted automatic core biopsy device. One such successful biopsy device is shown and disclosed in U.S. Pat. No. 5,526,822, U.S. Pat. No. 5,649,547, and U.S. Pat. No. 5,769,086, all of which are commonly owned by the assignee of the present application and are herein expressly incorporated by reference. This device, known commercially as the MAMMOTOME.RTM. Biopsy System, has the capability to active capture tissue prior to cutting the tissue. Active capture allows for sampling through non-homogeneous tissues, meaning that the device is equally capable of cutting through hard and soft tissue. The device is comprised of a disposable probe, a motorized drive unit, and an integrated vacuum source. The probe is made of stainless steel and molded plastic and is designed for collection of multiple tissue samples with a single insertion of the probe into the breast. The tip of the probe is configured with a laterally disposed sampling notch for capturing tissue samples. Orientation of the sample notch is directed by the physician, who uses a thumbwheel to direct tissue sampling in any direction about the circumference of the probe. A hollow cylindrical cutter severs and transports tissue samples to a tissue collection chamber for later testing.
While the MAMMOTOME Biopsy System functions very well as a core biopsy device, there are occasions when, because of the size of a lesion, or its location, it may be advantageous to use a core biopsy device of a type disclosed in U.S. Pat. No. 5,111,828, to Kornberg et al., also expressly incorporated by reference herein, wherein the tissue receiving port is disposed at the distal end of the device and is oriented axially rather than laterally. A disadvantage of this type of device, however, is the lack of ability to effectively and efficiently draw tissue into the receiving chamber prior to and during the tissue cutting process. A second disadvantage is the requirement to withdraw the device from parent tissue and remove the first specimen, reassemble the device, then reintroduce the device for each desired specimen. A third disadvantage is the necessity of manually handling each specimen obtained.
On other occasions, the ability to sample any selected area of a cavity wall from within the cavity may be important, which ability requires the use of a flexible probe.
Furthermore, it is desirable during the biopsy process to "stage" the spread of a cancer. For example, breast cancer starts in the milk ducts, the mammary glands. The initial change towards breast cancer is now thought to be the development of atypical ductile hyperplasia. The next step is thought to be represented by ductile carcinoma in situ. Finally, the last step in the development of breast cancer is infiltrating ductile carcinoma. By the time the breast cancer has reached the stage of infiltrative ductile carcinoma, breast cancer cells have developed the ability to migrate from the duct of origin, disassociate themselves from one another, and enter vascular structures, such as the lymphatic channels. When these malignant infiltrative ductile carcinoma cells enter the vascular system, they can spread or metastasize to other parts of the body. It is this metastatic process that ultimately leads to death from breast cancer.
When breast cancer cells enter the lymphatic system, they metastasize in an orderly fashion to regional lymph nodes. Drainage can occur to the axillary lymph nodes, the supraclavicular lymph nodes, the lateral thoracic lymph nodes, and to the internal mammary lymph nodes.
It is the current standard of practice to determine if breast cancer cells have extended to regional lymph nodes by surgically performing an axillary lymph node dissection known as lymphadenectomy. In this open surgical procedure, a relatively large incision (5-10 cm), is made at the axilla (the armpit). Through this incision, a relatively large volume (15 to 30 grams) of fatty tissue and lymph node tissue are removed.
During this process, anywhere from 10 to 30 lymph nodes can be recovered and submitted to pathology, where each of these lymph nodes is examined for the presence or absence of metastatic breast cancer. Based on positive lymph node findings, systemic therapy will be given to the patient with breast cancer, including chemotherapy. If, on the other hand, the lymph nodes of the axilla are free of metastatic disease, then the use of systemic therapies is limited.
Surgical lymphadenectomy carries a low mortality, but high morbidity. The most common morbidity is the development of lymph edema in the arm, which is ipsilateral to the axilla dissected. The development of lymph edema in the ipsilateral arm is, at times, a debilitating complication.
It has been shown in the examination of lymphatic drainage of melanoma, and now shown in the lymphatic drainage of breast cancers, that lymphatic drainage patterns can be defined by the injection of a radioisotope (or other traceable marker such as blue dye) into the bed of the tumor. The isotope (or dye) is then followed, either visually, with a gamma camera imaging system, or with a Geiger counter-type of counting system.
The spread of cancer cells is orderly, the first lymph node reached by the drainage channels from the infected breast containing the most cancer cells. Consequently, the first lymph node in the draining system is referred to as the "sentinel" lymph node.
It has been further shown, if one simply removes the sentinel lymph node, the determination of whether or not breast cancer has metastasized to the regional lymph nodes of the axilla can be established without excision of the remaining lymph nodes in the axilla. The surgical removal of only one lymph node greatly reduces the complications of lymph node surgery including the morbidity of lymph edema.
It would be desirable to further reduce the morbidity of the axillary sentinel lymph node biopsy if instrumentation were available to allow the sentinel lymph node to be identified and removed percutaneously with as little effect as possible to the surrounding tissue structure. The apparatus described in this patent can be introduced percutaneously through a small skin opening and directed to the sentinel lymph node thus eliminating open surgical exploration. Consequently, sentinel lymph node biopsy could be accomplished as an office procedure, eliminating hospitalization and minimizing the recovery period.
The elements of a percutaneous sentinel lymph node biopsy are as follows: The tumor site in the breast is injected with a radioisotope (such as technicium 99 m labeled sulfur colloid) which travels via the lymphatic channels to the sentinel lymph node. The sentinel lymph node then becomes radioactively visible, or "hot." The apparatus hereafter described is able to identify or locate the radioactive lymph node through auditory and other signals, indicating when the apparatus is adjacent to the sentinel lymph node. The apparatus is further able to then characterize or "visualize" the surrounding tissue with the associated ultrasound portion of the apparatus. It is important to identify the associated structures adjacent to the lymph node, because relatively large blood vessels (arteries, veins,) and nerves traverse the axilla. With the combination of percutaneous Geiger counter identification and percutaneous ultrasound identification, the sentinel lymph node can be identified and biopsied without entering a major blood vessel or severing a major nerve.
With a small entry site, no suturing would be required (the procedure would be percutaneous), and the patient could be sent home with a simple band-aid over the axillary entry site. The following day, the patient would receive the results of the percutaneous sentinel lymph node biopsy determining whether or not metastatic disease is present or absent in the sentinel lymph node draining the affected breast.
Instruments are known in the prior art which could be adapted to perform some of the procedures outlined above. For example, U.S. Pat. No. 5,111,828 to Komberg et al. discloses a percutaneous excisional breast biopsy device having a cannula, open distal and proximal ends, and a sharp cutting surface on the distal end. A stylet extends through the cannula and includes a distal puncturing end. A localization guide wire is used to direct the instrument to a biopsy site. The cannula is moved distally to cut a desired tissue specimen, after which a descending element is pushed to the distal end of the tissue specimen, then pulled proximally to sever the specimen completely from surrounding tissue.
A significant disadvantage of the Kornberg approach is that only one tissue sample may be obtained for each insertion of the instrument into the patient's body to the biopsy site. Once the descending element has been pulled to sever the tissue sample, there is no opportunity to repeat the procedure while the instrument remains in place. Also, no means is provided to ensure that tissue to be sampled is drawn toward the distal end of the cannula 2 (or "actively captured"), thereby reducing tissue sampling efficiency.